Jia L. Song, Ph.D.

Teaching

BISC 615 Developmental Biology

BISC 207 Introductory Biology

Research Interests

The potential for forming a new organism begins at fertilization, when the sperm meets the egg. Across species from the worm to the human, development of the newly fertilized egg to a juvenile or an adult requires the careful regulation of cell growth, differentiation, and morphogenesis. Different cell types make different sets of proteins, even when their genomes are identical. What makes each cell type unique is a direct result of differential gene expressions mediated by transcription factors and signaling molecules in response to chemicals and proteins in the cell and the environment. Dysregulation of important genes involved in developmental decisions can lead to human diseases. Our research addresses one of the fundamental questions in developmental biology: How are genes regulated during early development?

My laboratory investigates the regulatory roles of microRNAs (miRNAs) in early development. miRNAs are a class of non-coding RNA molecules that have recently been discovered to repress gene expressions in animal cells. miRNAs are critical for many aspects of life, including the development of an organism and physiological functions of cells and tissues.

We established the use of the sea urchin embryo as an animal model to elucidate how miRNAs control gene regulatory networks (GRNs) and signaling transduction pathways that drive developmental programs, pattern formation, and cell motility in an embryo. The sea urchin model has an exceptionally well-studied GRN and most of its miRNA families consist of a single species, which makes it amenable to unique, powerful functional analysis. Integrating state-of-the-art proteomics, bioinformatics, and molecular analyses, my research has revealed the function of miRNAs as integrators of developmental pathways. Since miRNAs, GRNs, and signaling pathways are evolutionarily highly conserved, our research serves as a paradigm of understanding the general function of miRNAs as important integrators of GRNs and signaling pathways to power development in making a functional embryo.

Current Projects

Our research areasare:

1. miRNAs modulate signaling transduction pathways to impact early development

Signaling transduction pathways are critical in early development, yet the role of miRNA regulation of these pathways is still lacking. Both Wnt and Delta/Notch signaling pathways are evolutionarily highly conserved and important in cell specification and differentiation. The goal of this project is to understand how miRNAs regulate these signaling pathways, and the impact of miRNA regulation in development.

We have previously established that microRNA-31 (miR-31) is one of the four critical miRNAs necessary to rescue developmental defects induced by the knockdown of miRNA biogenesis enzymes, indicating its importance in early development. As part of our goal to define miR-31’s function in the embryo, we bioinformatically searched for miR-31 targets genome-wide and compared the proteome of normal and miR-31 knockdown embryos, since animal miRNAs typically mediate their gene targets by translational repression. From these analyses, we identified that several genes that control cell motility were regulated by miR-31, including a small GTPase Arf6. We have shown that Arf6 protein was increased in miR-31 knockdown embryos compared to the control, indicating that miR-31 suppresses Arf6. Based on these results, we hypothesized that miR-31 suppresses genes that mediate the mechanics of cell motility.

miR-31 plays a key role in development and diseases by regulating genes important for cell differentiation, proliferation, apoptosis, and cell motility. However, miR-31 has been examined mostly in the context of cancer, and its role in development needs to be better understood. The goal of this project is to advance our understanding of how miR-31 integrates and cross-regulates GRNs and signaling pathways to impact development.